The invention relates to a process for retarding the formation of corrosion and/or removing existing corrosion deposits on a metal surface where the metal is in contact with air. The process comprises contacting said metal surface with an oxime in an amount effective to retard the formation of corrosion on the metal surface.
The formation of corrosion (typically Fe2O3, commonly known as rust) on metals is a problem whenever metals are exposed to oxygen and/or moisture. It is known that methyl ethyl ketoxime (MEKO) can be applied to xe2x80x9cclosed aqueous systemsxe2x80x9d such as boilers, which are mechanically deoxygenated systems, to protect the interior surface of a metal tube, pipe, or other enclosure. The typical dosage of MEKO used to control corrosion in a utility circuit, such as boiler, is from 30-80 ppb. It is believed that MEKO controls corrosion in the feedwater circuit of the boiler by scavenging oxygen and forming a corrosion-resistant oxide film on the waterside metallic surfaces. See, for instance, U.S. Pat. No. 4,487,745. In such closed systems, the amount of oxygen is minute. For instance, boiler water contains less than 100 pbb of oxygen, typically contains less than 10 ppb of oxygen, so there is little oxygen for the MEKO to scavenge.
In contrast to such a system, an xe2x80x9copen systemxe2x80x9d for purposes of this disclosure is one where the outer surface of the metal comes into contact with air. Air is known to contain about 19.8% by weight oxygen or 198,000,000 ppb. In view of this great amount of oxygen, it is not believed that MEKO would effectively retard corrosion of surface metals in a open system exposed to air.
A kiln is an open heating system with a refractory lined chamber used for the calcination of lime, magnesia, cement, and ores. Kilns are used for drying lumber where they function as a large oven-like chamber in which temperature, air moisture, and air circulation are regulated to allow proper drying of the lumber. A lumber kiln is a large oven like chamber which does not have refractory or even insulation in may cases. The structural members and sometimes the walls are bare, unpainted and uncoated steel.
Kilns are used to dry lumber in order to reduce the tendency of the lumber to rot and to control bending, cracking and splitting of the lumber in use. Lumber in a kiln is typically dried with steam produced by heating water with natural gas, wood waste products or hot oil. The steam is directly injected into the kiln through perforated pipes, by atomized sprays, or through coils which heat the lumber. Roof ventilators open, when the humidity of the kiln is too high, to let damp hot air out and cold air containing air into the kiln chamber.
Kilns have several openings where air can enter. These openings are typically found at the top and the sides of the kiln. In addition to refractory materials, a kiln contains many metal components for support. Typically these metal supports are made of steel and are subject to corrosion by incoming air and moisture.